Moenkopi and Chinle Formations
Clastic red beds were laid down in shallow-water on top of the eroded Paleozoic surface early in the Triassic. These sediments were deposited on flood plains by streams on an expansive lowland that was slightly sloped in the direction of an ocean to the west. Mud built up in tidal flats to become the mudstone of Moenkopi Formation. Examples of this formation, some that still show fossilized ripple marks and mudcracks, can be seen in the northern and western parts of the park.
Another period of erosion returned, creating a third unconformity. The brightly-colored shales of the slope-forming Chinle Formation were laid down on top of this eroded surface. Petrified wood from the Petrified Forest Member of the Chinle is sometimes found at the base of Chinle slopes.
Read more about this topic: Geology Of The Canyonlands Area